Treats gbufferchannel special and allows it to act as both a custom and native property at the same time.  This means we'll retain a user-set value in all cases rather than forcing a default 0 value in certain situations.
Treats gbufferchannel special and allows it to act as both a custom and native property at the same time.  This means we'll retain a user-set value in all cases rather than forcing a default 0 value in certain situations.

git-svn-id: a3b746cc1383a42926249ed33eaccad697259b1b@14954 896c8824-d3f5-0310-9c61-ac502b9a79dc

blurstudio/cross3d